Has your pH etc altered suddenly? Have you added any rocks etc to the tank?

What is the pH KH of your tap water?

It is easy to raise pH, hardness etc, but much harder to lower it.

A pH of 8.4 is a bit high, great for the Swortails, the other fish will cope with it, as long as it is stable. What fish don't like is sudden changes in pH, my advise is to leave well alone, and keep fish that suit your water conditions unless you really know what you are doing.

The buffer you are thinking about is actually your KH, or carbonate hardness, if you have a high KH, your pH will normally be very stable, with a low KH, pH can swing wildly.

There are plenty of ways to lower pH, hardness etc, but stay away from shop bought chemical solutions, they tend to be short term (Bad for the fish) and often don't work very well.

If we can sort out the problem (If it is a problem) then we can come up with some suggestions.

the pH did not change suddenly. But truthfully I doubt it really changed at all... a few days ago I tested my water when I got 5 in 1 tester kit, and thats when I noticed the high pH and KH. I cleaned the tank yesterday, I did about a 30% water change. I expected the pH and KH to be lower, but they did not. No I did not add any new rocks but I did add new artificial plants last week.

wow... I never expected the water to be that hard. Also explains why everything is still very high. What should I do? Or should I just leave it alone (my fish do not seem bothered by the pH or KH levels.)?

It's a bit hard for the Neons etc, but you won't be the only one keeping them in water like this.

Most fish are now commercially bred, they can cope with a much higher spread of water parameters than wild caught fish as long as they have time to get used to it when you buy them, but chances are your local LFS also has hard water (Ask them).

If you wanted to specalise in Amazon and other softwater fish, you would need to soften your water, but by then you would have learnt how to do this safely.

The main thing to avoid is sudden changes of pH, hardness etc, so I really would leave it.

One other thing (Sorry). Chinese Algae Eaters can be a real pain when they get older, they eat less algae, often become aggressive, and will rasp on larger fish etc. They can reach 8 inches and are a bit large for your tank.

PS one other thing, get a jug of tap water, leave it for 24 hours, then do a test on it, this will give you a base line that you can use to see if your tank water is being affected by anything in your tank.

I was told about the Chinese algae Eater. I'm just goning to keep him for now but when he gets older I'm gunna get rid of him. The tetras really do not seemed bothered by the pH or the KH. I might just leave it. but I'm going to keep a good eye on the levels.

What I do is place some aquarium peat into the filter. That will lower your KH and pH slowly so no fish gets stressed. Always go with the natural ways.
Live-bearers like Platy, Swordtails, Guppys will do better in hard waters IME.
For example, I have 6 aquariums connected to the same sump-filter that had lots of peat in it. pH was at 6.5 and the Guppys had lots of skin parasite problems causing lots of Guppy loss.

Month and half (to be precise, the beginning of November) ago I took the peat out and replaced it with lots of tufa rock and conditions already improved. No more deaths.

It is good if you can get the pH at about 7.5 it is good for both fish IME.

swordtails, like most poecillids, breed really quickly and easily, so don't worry about that. all you need is a male and 2 females (sometimes, you don't actually need the males in the same tank!). neons are more difficult though. they'll probably need soft acidic water to breed, but I don't know much about that, only that difficulty of breeding is "moderately difficult"_________________New to fishkeeping? Click the banner